The present disclosure relates to additive manufacturing systems for building three-dimensional (3D) parts with layer-based, additive manufacturing techniques. In particular, the present disclosure relates to print head assemblies for use in fused deposition modeling systems.
A fused deposition modeling system is used to build a 3D part or model from a digital representation of the 3D part in a layer-by-layer manner by extruding a flowable part material. The part material is extruded through an extrusion tip carried by an extrusion head, and is deposited as a sequence of roads on a substrate in an x-y plane. The extruded part material fuses to previously deposited modeling material, and solidifies upon a drop in temperature. The position of the extrusion head relative to the substrate is then incremented along a z-axis (perpendicular to the x-y plane), and the process is then repeated to form a 3D part resembling the digital representation.
Movement of the extrusion head with respect to the substrate is performed under computer control, in accordance with build data that represents the 3D part. The build data is obtained by initially slicing the digital representation of the 3D part into multiple horizontally sliced layers. Then, for each sliced layer, the host computer generates a build path for depositing roads of modeling material to form the 3D part.
In fabricating 3D parts by depositing layers of a modeling material, supporting layers or structures are typically built underneath overhanging portions or in cavities of objects under construction, which are not supported by the part material itself. A support structure may be built utilizing the same deposition techniques by which the part material is deposited. The host computer generates additional geometry acting as a support structure for the overhanging or free-space segments of the 3D part being formed. Support material is then deposited from a second nozzle pursuant to the generated geometry during the build process. The support material adheres to the modeling material during fabrication, and is removable from the completed 3D part when the build process is complete.